Panoramic cameras, that is, cameras capable of taking photographs with unusually wide horizontal fields of view, have existed for some time. This disclosure is concerned with panoramic photographs taken with rotational and swing-lens panoramic cameras.
A rotational panoramic camera rotates the camera body during the taking of a photograph, and may be capable of taking photographs with horizontal viewing angles of 360 degrees or more. The film inside the camera also moves in synchronization with the camera rotation. These cameras are sometimes called “Cirkut-type” cameras, after an early commercial model. A well-known contemporary camera of this type is the Roundshot, made by Seitz Phototechnik AG of Switzerland.
A swing-lens panoramic camera rotates the lens and an exposure slit but not the camera body. The film is held stationary in a curved shape and the image is painted onto the film as the exposure slit passes by it. This type of camera usually can take photographs with horizontal viewing angles just less than 180 degrees. Two well-known camera models that operate on this principle are the Widelux and Horizon cameras.
Digital panoramic cameras are also available. A digital panoramic camera rotates the entire camera while repeatedly reading image data from a row or set of rows of electronic light sensors behind the lens.
Most panoramic cameras have fixed focal length lenses that are fixed in position in relation to the film, and thus have a limited vertical field of view that is not adjustable. Some cameras provide a lens shift capability wherein the lens optical axis may be moved relative to the film. This allows the vertical field of view of the camera to be shifted up and down, but does not increase the vertical field of view. However, many panoramic cameras do not provide a lens shift capability.
Often, a panoramic camera is held level, with its rotational axis substantially vertical during the taking of a photograph so that the horizon in the photograph appears straight and level and to minimize distortion of objects in the photograph. If the camera is tilted so that its rotational axis is at an angle to vertical, objectionable camera-tilt distortion may be introduced into the photograph. Many camera models have level-indicating devices built into the camera bodies to aid the photographer in leveling the camera.
A panoramic camera may also be used with its rotational axis substantially horizontal in order to achieve an unusually large vertical field of view, or at some other angle with respect to vertical. Generally, however, these cameras are used to achieve a large horizontal field of view and are therefore used with their rotational axes substantially vertical.
This desire to keep the camera level and lack of adjustability may limit the photographer's ability to capture the desired elements of a scene. For example, the photographer may wish to photograph an entire building, the height of which would fit within the camera's vertical field of view, but be unable to include the top of the building in the photograph because of the requirement to keep the camera level to avoid distortion.
The photographer may be able to take the photograph from a more remote vantage point, thus allowing the camera's vertical field of view to encompass the entire building. However, this results in an undesirable loss of resolution of the subject in the resulting photograph, and a more remote vantage point may not be available.
In this situation the photographer has historically been faced with the choice of photographing the available vertical field of view which is not the desired field of view, tilting the camera to encompass the desired subject and accepting the resulting distortion, or using a more remote vantage point if one is available and accepting the resulting loss of subject resolution.
There is a need for a method of allowing the photographer to tilt a rotational or swing-lens lens panoramic camera, take a photograph that includes the resulting distortion, and recover an undistorted representation of the photograph later.